Legally, most professions are not supposed to work more than 48 hours per week. In many industries such as the caring industry, workers can be asked by their employers to voluntarily sign an Opt-Out Agreement which is legal, i.e. you opt-out of the 48 hour limit and agree that you can work for more than 48 hours per week.
The Opt-Out is not a condition of your employment and it must remain optional and voluntary. Therefore, even if you’ve signed your contract with an Opt-Out in place, as a homecare worker you have the legal right to opt back in to the 48 hour limit at a later date – you have to give your employer a minimum of seven days written notice by law to do this (check your contract in case it requires a longer time scale to Opt back in, as this is allowed).
You should not be subjected to any detriment by refusing or proposing to refuse to sign an Opt-Out agreement. If you are an employee and are dismissed because you refuse to sign an Opt-Out clause then this could be an automatically unfair dismissal and you could potentially make a claim to an Employment Tribunal as is your homecare worker right.